An enhanced circular polarization near‐field focused antenna array by director patches

Abstract

This paper presents an enhanced circular polarization (CP) near‐field focused (NFF) antenna array. There exist three advantages for the CP NFF antenna. First, this study provides an effective way to realize the CP and NFF simultaneously and do not need to design a specific patch shape for CP, which provides more freedom to change the patch shape for improving other performances. The effective way is arranging the element excitation according to maximum power transmission efficiency theory under the condition of a CP testing antenna. Second, the array element consists of a driven and director patches, and the director patches tilt the element beam from broadside direction to focal point, and then obviously enhance the electric field focusing gain. Third, the proposed array antenna achieves much less size of focal point by using much less element number than published papers. The curves for the impedance and axial ratio (AR) as function of frequency, focus width and depth are analyzed. The simulated and measured results basically agree.